Drum separator



Dec. 7, 1954 E. J. MAUST 2,696,300

DRUM SEPARATOR Filed Feb. 23, 1951 2 Sheets-Sheet l xNvENToRERA/STJMAc/s T BY @Aiwa/MJ AT1-ORN 5 Dec. 7, 1954 E. J. MAUST 2,696,300

DRUM SEPARATOR Filed Feb. 25, 1951 2 Sheets-Sheet 2 INVENTOR ATTORNSttltS Patent" DRUM SEPARATQR Ernest J. 'Maus Packanack Lake, N. I.,assignor to West- Iern Machinery Company, New York, N. Y., a corporationfof Utah Application February 23, 1951,1Serial No. 212,249

s claims. (cl. 209-1125) 'This .invention relates Vto 7the separation bygravity of solid `particles vof different .specific gravities in a heavyor dense liquid or medium, and has for its object the provision of.certain improvements in a ldrum type separator for effecting thecontemplated separation.

rIhe heavymedifa separation process, sometimes called the sink and floatprocess, consists in introducing a mixturetof the solid particles ofdifferent specific gravities to be separated, such for example as acrushed ore agglomerate, into a heavy (dense) liquid or medium of aspecific gravity between .the specific gravities of the .solid-particles (fe. g. valuable and Waste constituents vof the crushedmineral .ag-glemerate) to be separated. The solid particles having aspecific `gravity less than that of .the heavy medium float to thesurface, while the solid particles having -a specific gravity greaterthan that of lthe heavy medium sink in ythe medium. Usually, the heavymedium is an aqueous suspension of a finely divided solid, such, forexample, asfinely ground galena, barytes, silica, heimat-ite, magnetite,ferrosilicon and mixtures of one or more of thesewith other minerals.

VGone :separators have heretofore been commonly used for carrying loutlthe heavy media .separation process. While separators of the drum typeare known and have been used in a small way, they have given in practicevery indifferent results, .and have attained no favor in the fart. Ihave discovered `that remarkably improved results are obtained when thelifting vanes (commonly called .sink lifters) vare solid rather thanperforated as has heretofore been the case. Accordingly, the inventionis characterized in that the sink -lifters are solid and have asubstantial portion thereof inclined in the direction `of lrotation ofthe drum thereby forming an imperforate` pocket for settled soiidparticles and medium between the lifter and the adjacent inner surfaceof the drum. As the drum rotates, the imperforate pockets formed by theysolid lifters continuously move a very large 'volume of medium from offthe bottom of the pool ofy medium in the vdrum and return it to the poolbehind the customary baille or skirt board, but beneath the surface ofkthe pool. Consequently, a continuous agitation of the medium ltakesplace beneath the surface 'of the pool sufficient to maintain thesuspension in the medium of its finely divided solid constituentkwithoutany mechanical disturbance of the pool and with no substantialdisturbance at `.the surface of the pool.

The invention will be best understood from the following descriptiontaken in conjunction with the accom* panying drawings, in which:

Fig. l is Va sectional side elevation of a drum separator embodying theinvention, and

Fig. y2 is :a -cross section of the separator taken 0n the sect-ion line2'-2"of Fig. 1.

The separator comprises a hollow cylindrical drum 5, advantageously madeof welded, rolled steel plate, which is supported for rotation on fourrollers 6 mounted on the foundation, and riding on two steel tires 7 xedto the outside of the drum near each end. The drum is rotated by asprocket 8 (fixed to the outside) and a cooperating driving means (notshown). The ends of the drum are partially closed by annular plates 9and 10, with their circular openings in the axis of the drum.`

The circular opening of the plate 10 constitutes in effect an overflowwier for the iloat fraction of the separation, and is of larger diameterthan the circular opening of the plate 9.

ICC,

A multiplicity :of longitudinal sink lifters 111 are -secured inoircumferentially spaced relation to 'the .inside surface of the drum.The litters, of solid (imperforate.) steel plate or the like, are boltedor Welded -to diaphragm flanges -12 lwelded to the inside surface of thedrum. A substantial portion tof each lifter is inclined (with respect to-the radial axis) in lthe direction of 'rotation of the drum, indicatedby the arrow near the top of Fig. 2. Preferably, about thalf yof theouter free portion of the lifter is so inclined, at about lan .angle of45 with respect tothe radial axis, vwhile the inner yportion (attachedto flange `12) of the lifter is radially positioned, thereby providing alongitudinal imperforate pocket 13 .between the lifter and the adjacentinner surface of fthe drum. The lifters are uniformly spaced a fewinches apart (e. g. 3 to 8 inches) around the entire inner surface `ofVthe drum, and extend inwardly a yfew inches (e. g. 5 to 10 inches) fromthe inner surface of the drum. In -a drum about l() feet long and yl0feet in diameter, the lifters may advantageously be spaced about 7inches apart, and the inner edge of the lifter may be about 7 inches(radially.) `from -the .inside surface 'of the drum.

A structural steel frame 14 is mounted on the foundation, at each end ofthe drum, and its horizontalmernbers 14 extend through the circularopenings of the end plates 9 and 10 `and provide support for ythestationary lmembers within the drum. A longitudinal partition or baille(skirt board) 15 -is vertically mounted within the :drum on each side ofthe center longitudinal axis about midway between the axis and theadjacent inner surface of the drum. The `partitions 15 are secured tothe member 14 of the frame by straps `16, with `the lower edge of eachpartition about twice the distance (radially) from the inside surface ofthe drum as the tips or inner edges of the lifters 11. Thus, in theaforementioned 10-foot drum, the lower edge of each partition is about14 inches (radi ally) from the inside surface of the drum, and `henceabout 7 inches from the tips of the litters 11 Vas the latter passbeneath the partitions.

A feed chute 17 (for the mixture of solid particles to .be separated) ismounted on the frame 14 and extends through the circular opening of theend plate 9 into the drum, its depending discharge end .17' beingproximate the end (9) of the drum and terminating just below the .normalliquid level of ythe pool of heavy medium within the drum.

Heavy medium (of selected specific gravity) is sup# plied to the drum bymeans of a pipe 18, and intimately mixes with the feed in feed chute 17.Heavy medium, with the light or float fraction of the separation, over-'ilows through the circular opening of the end plate 10 into a dischargelaunder y19.. A discharge trough '20 for the heavy or sink fraction ofthe separation extends longitudinally through the drum, for the mostpart above the central axis of the drum and below the point where thelifters 11 pass the pocket-discharge position in their revolution. Thetrough is .appropriately secured `to the frame 14 by straps .21. The topof the trough is provided with end chutes 22, suitably attached to theends of the trough, for guiding into the trough such solid particles .asmight otherwise drop from the litters .11 intov the space between theends of the rotating drum and the adjacent ends of the stationary-trough.

In the operation of the separator, the drum is slowly rotated, e. g. atabout 2 R. P. M. in the case of the aforementioned 10-foot drum. Thefeed (along with fresh heavy medium) is introduced through the chute 17at one end of the drum and is submerged in the pool of heavy medium inthe separating compartment B between the partitions 15. The floatfraction rises to the surface and overflows from the drum into thedischarge launder 19. The heavy fraction sinks to the bottom of thedrum, is picked up by the lifters 11, carried to near the top of thedrum, and dropped into the discharge trough 20.

In accordance with the invention, the vanes of the lifters 11 are solidand act not only to convey the heavy or sink fraction of the separationout of the pool of medium and thence into the discharge trough 20, butalso act to circulate the medium beneath the surface or liquid level ofthe pool. This circulation of the medium beneath the surface of the poolprevents segregation of the nely divided solid constituent of the mediumand eliminates the necessity ot introducing medium under pressure, andthe rising velocity associated with the extraneous circulation ot themedium as heretofore commonly practiced in the art. This positivecirculation of the medium beneath the pool level allows the surface ofthe pool to be entirely quiescent, thus providing a pool having theVcharacteristics of the heavy media used in laboratory practice, givingseparating eillciencies superior to other apparatus where risingcurrents or agitating devices are employed to maintain suspension in themedium of its nely divided solid constituent.

As the solid or impertorate litters move upwardly from the bottom ot thedrum, they bodily move some medium from the bottom of the pool andreturn a substantial part ot it to the pool behind (on the right side inFig. 2) the baille or skirt board 15, but beneath the surface of thepool, and induce within the pool a positive and effective circulation otmedium, so that the ilnely divided solid constituent thereof ismaintained in suspension and only such amount of medium need be suppliedto the drum as overflows with the iloat fraction of the separation.Contrasted with the operation of such separators as the cone, the volumeof medium that need be circulated is reduced to less than one-half. Thisreduces the power and maintenance in the plant to a large extent, and isa distinct improvement in the art.

The solid litters thus induce a gentle, controlled agitation of theheavy medium in the drum as a result of the passage of the littersthrough the medium as the drum rotates. The arrows at the bottom of Fig.2 indicate generally the nature of this agitation. The rising litterscarry the liquid level to a slightly higher level (a) in thelongitudinal compartment A between the partition and the rising littersthan the level (b) in the main separating compartment B between thepartitions. Also, the litters moving through the medium bring the liquidlevel (c) in the longitudinal compartment C between the partition 15 andthe descending litters to a lower level than in the compartment B. Thus,there is a gentle flow of medium from the compartments A and C beneaththe partitions 15 into the compartment B. This flow of medium intocompartment B sets up a gentle circulation of the medium in thiscompartment where separation of the iloat and sink fractions mainlytakes place. The continuous circulation of the heavy medium minimizessegregation of its nely divided solid constituent, and provides aneffective mixing ot the medium with the solid particles to be separatedwithout substantial disturbance at the surface, and solids, tending tosettle near the bottom ot the drum, are continuously moved upwardly anda cleaner and more effective separation is thereby attained. Theclearance between the lower edge ot the partitions 15 and the tips ofthe litters 11 determines the velocity of the ilow of medium between thecompartment A (and C) and B, and the speed of rotation ot the drum, theradial width ot the litters and their circumferential spacing determinethe volume ot such flow. With a drum and litters of given dimensions,the slower the drum rotates the more closely should the lifters bespaced, to provide the contemplated volume of liquid flow fromcompartments A-C to compartment B. In the case of the aforementioned10-toot drum with litters of the dimensions hereinbefore specified and adrum speed ot 2 R. P. M., the volume of liquid ilow between compartmentsA and B is ot the order ot 2000 gallons per minute. With an overllowdepth ot 4 inches at the center of the circular opening in the end plate10, there is practically no disturbance at the surface of the poolwithin compartment B of the drum, and the speciilc gravity differentialbetween the fresh medium sup- 4 plied to the drum and the mediumassociated with the iloat overflow is only about 0.04.

' I claim:

l. In a separator ot the rotary drum type tor separating solid particlesof different specific gravities by the heavy media process including arotatable drum having impertorate cylindrical side and annular endwalls, each of the impertorate annular end walls being provided with asubstantially circular central opening, means for introducing heavymedium and solid particles to be separated into the drum through theopening in one of said end walls, means for discharging iloating solidparticles from the drum through the opening in the other of said endwalls, and a multiplicity of sink litters circumferentially spaced aboutand secured to the inner surface of the drum and adapted as the drumrotates to carry settled solid particles out of the medium to adischarge trough therefor, the improvement characterized by theprovision ot a longitudinally disposed stationary baille verticallypositioned within the drum on each side of its center axis and betweenthe axis and the adjacent inner surface ot the drum with the lower edgeof each baille spaced from the inner surface ot the drum, and furthercharacterized in that the sink lifters are solid and have a substantialportion thereof inclined in the direction ot rotation of the drum andform with the inner surface of the drum a multiplicity ofcircumferentially spaced irnperforate pockets.

, 2. In a separator ot the rotary drum type tor separating solidparticles ot different specic gravities by the heavy media separationprocess including a rotatable drum having impertorate cylindrical sideand annular end walls, each of the impertorate annular end walls beingprovided 'l with a substantially circular central opening, means forintroducing heavy medium and solid particles to be separated into thedrum through the opening in one ot said end walls, means tor dischargingiloating solid particles from the drum through the opening in the otherof said end walls, and a multiplicity of sink litters circumferentiallyspaced about and secured to the inside surface of the drum and adaptedas the drum rotates to carry settled solid particles out ot the mediumto a discharge trough therefor, the improvement characterized by theprovision ot a longitudinally disposed stationary baille verticallypositioned within the drum on each side of its center axis and betweenthe axis and the adjacent inner surface of the drum with the lower edgeof each baille spaced from the inner surface of the drum, and furthercharacterized in that the sink litters are longitudinally secured to theinside surface of the drum at intervals of from 3 to 8 inches apart andeach comprises a solid vane having an inner portion radially positionedwith respect to the axis of the drum and an outer portion inclined inthe direction of rotation ot the drum thereby forming an impertoratelongitudinal pocket along the inside ot the drum,

3. The improvement according to claim 2 further characterized in thatthe lower edge ot each baffle is radially spaced from the adjacent innersurface ot the drum by A about twice the distance that the inner tips ofthe sink liifters are radially spaced from the inner surface of the rum.

References Cited in the ille of this patent UNITED STATES PATENTS`Number Name Date 1,839,804 Perkins Ian. 5, 1932 2,479,141 Smith Aug.16, 1949 2,482,747 Davis et al Sept. 27, 1949 2,521,152 Davis Sept. 5,1950 2,624,461 Falconer Ian. 6, 1953

